Computing devices may execute software applications, such as games, web browsers, messaging services, or social-networking applications. With social-networking applications, users may connect, communicate, and share information with other users in their social networks. Applications may interface with hardware and software to provide functionality to a user. For example, a mobile device may include applications that access sensor output to locate the client device, such as output from a global positioning system (GPS) chipset on the mobile device. As another example, applications on a computing device may use functionality of an operating system, such as memory management functionality, during execution of the application.